Illustration: David A. Aguilar (CfA)
By Michelle Starr
While it’s not strictly impossible that life in the universe exists in an as-yet-unknown form (say, silicon-based), we don’t really know how to look for it. We do, however, know how to look for the conditions that have given birth to the life forms we know — that is, the conditions on our home planet, Earth.
This is the Kepler mission: to locate planets enough like Earth to be considered habitable. There are several key factors to this. First, the planets must be in the “Goldilocks” zone — that is, not too hot, not too cold, but juuuust right. This refers to the planet’s orbit position around its star: a distance where it’s not so close that it’s too hot for liquid water, but not so far that it’s so cold all water freezes.
In addition, the planet needs to be rocky — like Earth.
Among the recent crop of eight new Kepler planets discovered in the Goldilocks zone around their stars — announced at a meeting of the American Astronomical Society on January 6 — two are the most similar to Earth of any of the 1,004 Kepler planets identified to date.
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